He was a Progressive Conservative member of the Legislative Assembly of Manitoba from 1977 to 1981, and served as a cabinet minister in the government of Sterling Lyon.
[2] MacMaster first ran for public office in the federal election of 1965, as a New Democrat in the northern Manitoba riding of Churchill.
He received 3306 votes, finishing third behind Tory Robert Simpson and Liberal Francis Bud Jobin.
[5] He was dropped as Northern Affairs minister on November 15, 1979, but kept his other responsibilities until the Lyon government was defeated in the election of 1981.
[4] He has not sought a return to political life since this time, but is very involved in community activities and projects in the Lac du Bonnet area.